Flat leaf springs?

[j-rho]

I run my '67 Camaro (http://www.rhoadescamaro.com/build) in SCCA autocross in a class that mandates I keep leaf springs.

The car is fairly light by Pro-Touring standards - under 3000 pounds, with about 625 pounds rear corner weight (under 500lbs. sprung corner weight).

To date I've been running composite leaf springs from Flex-A-Form - the lowest ones they could make, at a rate about what I want (250lb./in). I'm happy with the handling balance.



The problem is, even with the lowest springs they can make, the rear of my car sits much higher that I'd like. To combat this I've resorted to spacer blocks, 1.5"! Too much. Have already seen it causing some problems (axle moving around in relation to the leafs).

I'd like a leaf spring that allows me to run the ride height I want (which is actually even lower than the car is now) without any spacer block. To do this, will require a spring that is basically flat at ride height (so ~2" "free arch"), but allows for about 2" of bump and droop from there.

The Flex-A-Form guy (Mark?) said he couldn't do it, because of how the layers of his composite leafs are designed only to work in tension or compression, and as the spring passes zero/flat, it starts to get worked the other way. Makes sense but is unfortunate, as I really like the weight savings.

I'm not sure that steel would have the same problems though? I ordered a set of Global West's lowest multi-leaf steel pack, but they refused to do any de-arching of the springs before shipping them to me, saying it would cause safety problems? And that the springs would be low enough?

Is there another solution (that fits my rules) that I'm missing? A provider of lower or custom-arch'd steel leafs? When I inevitably have to have my Global West springs de-arched 2" or more, what real safety issues may arise as a result of the flat to negative-arch spring?

Thanks for the assistance!

[Bryce]

Here is another fiberglass leaf spring supplier: Composite Leaf Springs | Hyperco

I don't see an issue with de-arching the springs. But talking to the vendor that can de-arch springs would give some insight.

What I have done is build clamps for the front half of the spring, this holds the spring stack 'flatter' in the front. Then rear is curved and this is where you get your suspension travel from. Can you adjust your rear shackles to lower the car more?

Take a look at Chrysler drag racing 1/4 elliptical springs....

[j-rho]

I started with the Hyper Co (actually made by LiteFlex LLC) - car looked like a 4x4.

Bryce you're in SD - any place you know that can de-arch leafs?

[Bryce]

Jason,

I don't off the top of my head. I will be looking for a place soon though.

I usually call shops I like and trust and get recommendations from them.

Call Best of Show, hot rods and custom stuff and see if they have a source.

[72BBSwinger]

I would see what Hotchkis has. I run their rear leafs in my Dart and they are 0 arch at ride height. Rate wise they are only about 130lbs in my application.

[rustomatic]

Walt Hane at EPS uses flat springs in his vintage race cars; they're also narrower than stock. He does mostly Mustangs (and some Falcons), but surely would have some ideas for you...

I think Craig510 has some on his Falcon...

[Jon @ Hotchkis]

Jason, we have a set of 3" lowering leafs that are a 150-180lb rate and are flat at ride height.

If that won't work for you I would check with a company called Deaver Spring, they are up in Santa Ana. They are big in the offroad world and I know they used to make custom spring packs, I'm sure it would be no sweat for them to make a set for you.

[j-rho]

Jason, we have a set of 3" lowering leafs that are a 150-180lb rate and are flat at ride height.

Jon,What is the "free arch" of those leafs? How much force does it take to compress them:1", 2", 3", 4", 5", 6"? I get that '3" lowering leafs' may be enough info for most people but it bakes in assumptions about sprung weight and shackle length.What I need are leafs that go flat with about 475lbs. of load, and work at a 225-250lb/in. rate from there. Appreciate I will probably have to go custom.Thanks!

[dontlifttoshift]

Jason, try these guys EATON Detroit Spring, Inc. | The leading manufacturer of leaf and coil springs for the street rod and restoration industries

They have done several leaf packs for oddballs for us and we have always been pleased with the outcome.

[Jon @ Hotchkis]

Jon,What is the "free arch" of those leafs? How much force does it take to compress them:1", 2", 3", 4", 5", 6"? I get that '3" lowering leafs' may be enough info for most people but it bakes in assumptions about sprung weight and shackle length.What I need are leafs that go flat with about 475lbs. of load, and work at a 225-250lb/in. rate from there. Appreciate I will probably have to go custom.Thanks!

Jason, our 3" drop leaf has a free arch of 3.5" from the center of both mounting eyes to the top surface of the top leaf. I do not have the rate increase values at different heights.

Thanks.

[cornfedbill]

There are other alternatives like the Herb Adams modification. See https://www.pro-touring.com/cars-gen...did-70760.html

I am going to do this to my Nova to get the rear end down a bit.

This can give you a bit more lowering in addition to flatter springs.

[j-rho]

Thanks Bill for the link, can't modify the floor though.

Will probably end up pushing one of the custom options, and make do with what I can get for the big race starting next week.

[cornfedbill]

Thanks Bill for the link, can't modify the floor though.

Will probably end up pushing one of the custom options, and make do with what I can get for the big race starting next week.

Can you modify the spring pocket (a bolt-on part) to the point that it still fits under the stock floor?

[j-rho]

That part is somewhat open to interpretation...to be safe, I am not modifying mine. Even with another 1/2-3/4", wouldn't be where it needs to be.

[SLO_Z28]

Can you modify the spring pocket (a bolt-on part) to the point that it still fits under the stock floor?

Not without kicking himself up in to the cp class. The reality is if you did it no one could tell.

On to the origional question, l dont think what you want exists. You can get a lower rate spring in a composite, which will atain the ride height, but change the dynamics of the car. In steel there are a ton of wsys to get what you want.

[regal454]

Can you modify the spring pocket (a bolt-on part) to the point that it still fits under the stock floor?

Not much room to do that mod on a first gen without cutting the floor boards, maybe a 1/2" max.

I just saw NPD is selling the leaf spring front brackets with the bolt holes already raised for 2nd gen Camaros for $228! I think they are targeting hot rodders that do not own a 7/16" drill bit and a tape measure.

[j-rho]

Here is a Global West leaf next to a Flex-A-Form composite leaf.

Flex-a-Form has about 3.5" of free arch (measurement system isn't perfect since I'm not measuring bearing eyes front and rear). They are 1.5-2" too tall.

Using the same method of measurement, GW has 4.5" of free arch. Even if they are softer, this means they will be about 2.5" too high.

And boy are they heavy!! Car had mono leafs when I got it, and the composites are a combined 11lb. lighter than steel monos; these multi-leaf spring feel like they weigh over 50lbs. each, where the composites are more like 6-7 pounds. Rather significant.

The only advantage of the steel, is I should be able to have them de-arched down 2" or more, to get the ride height appropriate. And maybe swap out some of the helpers to up the rate if necessary.

No time to do that for a while though, will have to wait till after Nationals.

[Randy67]

Could a reverse-eye spring be used? That would get it down some more and maybe still keep some spring arch. Just a thought.

[19,69camaro]

Could you flip the bushing end on the composite springs? From the pictures on flex-forms site they look like they could be reversed for a gain of about a half inch. Not all that you wanted but a little here and there adds up.

[j-rho]

In the picture, the steel springs are reverse eye, and the composites have their eyes in the "flattest" orientation.